The radio frequency (RF) spectrum is a limited commodity. Only a small portion of the spectrum can be assigned to each communications industry. The assigned spectrum, therefore, must be used efficiently in order to allow as many frequency users as possible to have access to the spectrum. Multiple access modulation techniques are some of the most efficient techniques for utilizing the RF spectrum. Examples of such modulation techniques include time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA).
There is a wide variance in the performance of wireless networks. A conventional public wide area network (WAN), such as a CDMA cellular network, covers a large geographical area (on the order of 1 to 100 plus square miles), but has a relatively low bit-rate between each mobile station and each base station. These public wireless networks use regulated portions of the radio spectrum and are shared by many users. The infrastructure costs of public wireless networks are relatively high due to the size and complexity of the base station equipment.
Newer wireless networks, such as CDMA2000-EV/DV or 1XEV/DO networks, offer higher bit-rates (on the order to 2.4 MBps) and enhanced data services, such as web browsing. However, these networks also pack many users into a relatively small portion of the regulated spectrum. Still other types of radio networks, such as wireless local area networks (WLANs) or wireless personal area networks (WPANs) try to increase the throughput or bit-rate in unregulated spectrum and smaller coverage areas. For example, a WLAN IEEE-802.11 (or WI-FI) network may transmit at speeds up to 11 Mbps in Direct Sequence Spread Spectrum (DSSS) mode or at speeds up to 54 Mbps in Orthogonal Frequency Division Multiplexing (OFDM) mode. For the purposes of this application and the claims herein, the term “IEEE 802.11” includes the different versions of the IEEE 802.11 standard (e.g., IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, etc.).
However, an access point (or base station) in an IEEE 802.11 network may cover an area only a few hundred feet in diameter. In conventional network, each access point is connected to the core network (e.g., Internet) by, for example, a wireline Ethernet connection, a wireline backhaul connection, or a point-to-point wireless connection. In order to cover the same geographical area as a base station of a public wireless network, a large number of IEEE 802.11 network access points and a large wireline backhaul network are required. The resulting IEEE 802.11 based network may be more expensive to set up and operate (due to backhaul cost) than the public wireless network. Thus, there are always tradeoffs between and among the coverage areas, the maximum bit-rates, and the costs of different types of wireless networks.
Therefore, there is a need in the art for an improved wireless network architecture that overcomes the limitations of the above-described conventional wireless networks. In particular, there is a need for a wireless network that provides IEEE 802.11 (or equivalent) communication services to mobile stations or access terminals over a relatively large geographical area, without incurring the costs of a large wireline backhaul network to couple all of the IEEE 802.11 (or equivalent) access points to a core network.